[A comparative ultracytochemical and biochemical study of the ATPases of the choroid plexus in aging].

A complex study was undertaken on the ATPase and an ouabain-sensitive potassium-dependent p-nitrophenylphosphatase part of the Na, K-ATPase complex at the ultrastructural level, in addition to a biochemical assay of the total ATPase activity and activity of Na, K-ATPase of the choroid plexus (CP) of brain ventricles in adult (6-8 mo) and old (26-28 mo) rats. A correlation between the results of cytochemical and biochemical analyses was noted pointing to an age-related decrease in ATPase activity of the CP. Especially marked was the decrease in Na, K-ATPase activity that evidenced for the reduced level of liquor production in the CP during aging. Identified were the sites of a predominant localization of enzymes on the plasma membranes and intracellular organelles of the CP epitheliocytes. The latter fact was associated with their involvement in the processes of energy transformation and transport of substances. The data of the ultracytochemical and biochemical analyses, together with the results of the ultrastructural investigation, indicate an age-related decrease in the functional activity of the CP that represents one of the essential links in the mechanism of brain aging.